Holography is a technique that allows the light scattered from an object to be recorded and later reconstructed so that it appears as if the object is in the same position relative to the recording medium as it was when recorded. The image changes as the position and orientation of the viewing system changes in exactly the same way as if the object was still present, thus making the recorded image appear three dimesional. The technique of holography can also be used to optically store, retrieve, and process information. While holography is commonly used to display static 3-D pictures, it is not yet possible to generate arbitrary scenes by a holographic volumetric display. Holography was discovered in 1947 by Hungarian physicist Denes Habor work for which he received the Nobel Prize in 1971. It was made possible by pioneering work in the field of physics by other scientists who resolved technical issues that previously made advancements impossible. The discovery was an unexpected result of research into improving electron microscopes at the British Thompson-Houston Company in Rugby, England.One of the most promising recent advances in the short history of holography has been the mass production of low- cost solid state lazers.

Friday, February 20, 2009

The Sombrero Galaxy (also known as M104 or NGC 4594) is an unbarred spiral galaxy in the constalation Virgo. It has a bright nucleus, an unusually large central bulge, and a prominent dust lane in its inclined disk. The dark dust lane and the bulge give this galaxy the appearance of a sombrero. The galaxy has an apparant brightness of 9.0, making it a galaxy that can easily be seen with amateur telescopes. The large bulge, the central huge black hole, and the dust lane all attract the attention of professional astronomers. As noted above, this galaxy's most striking feature is the dust lane that crosses in front of the bulge of the galaxy. This dust lane is actually a symmetric ring that encloses the bulge of the galaxy. Most of the cold atomic hydrogen gas and the dust lies within this ring. The ring might also contain most of the Sombrero Galaxy's cold molecular gas, although this is an inference based on observations with low resolution and weak detections. Additional observations are needed to confirm that the Sombrero galaxy's molecular gas is constrained to the ring. The Sombrero Galaxy has a relatively large number of globular clusters. Observational comparable to other galaxies with large bulges. These results have been repeatedly used to demonstrate that the number of globular clusters in galaxies is thought to be related to the size of the galaxies' bulges. The surface density of the globular clusters generally follows the light profile of the bulge except for near the center of the galaxy.